Generally, before someone comes into the country as the partner of a British citizen on a family visa, they must submit a range of evidence proving their relationship is real.

This might include:

records of email, text and phone conversations

holiday photos

flight tickets

leases on shared apartments

mortgage documents

We simply don't know if Ms Markle has begun this process already.

Will they have to go to Croydon?

The initial visa granted will last up to two and a half years, after which time it must be renewed.

Home Office staff can ask couples to come to the Croydon headquarters of the UK Visa and Immigration service or one of six other immigration centres around the country for an interview, although not everyone will have to do this.

After coming in on a family visa, individuals must wait five years before permanent residency is granted, also known as "indefinite leave to remain".

Life in the UK

Only then can they apply for citizenship, provided they have spent no more than 270 days outside the UK in the past three years.

At this point, Ms Markle will have to take a test with questions on life in the UK, costing £50.

According to the website Life in the UK Test Web, this could include multiple-choice questions such as "Who is married to the Queen of England?" and "What is the relationship between the monarch and the government?"

In case Ms Markle needs any help, the Home Office produces an official handbook with everything she will need to know for the test.